Device for a layerwise manufacturing of a three-dimensional object and method for adjusting an optical system of the same

ABSTRACT

A device ( 1 ) for manufacturing a three-dimensional object by a layer-wise solidification of a building material at positions in the respective layers corresponding to the object is provided. The device has an energy source ( 6 ) that emits a beam ( 9 ) for solidifying the building material, a scanner ( 8 ) that selectively directs the beam ( 9 ) to different positions in a building plane ( 11 ), and a deflection mirror ( 7 ) that deflects the beam ( 9 ) coming from the energy source ( 6 ) to the scanner ( 8 ). The beam ( 9 ) from the energy source ( 6 ) to the scanner ( 8 ) runs in a space ( 13, 14 ) secluded from the outside and an adjustment mechanism ( 16 ) for the alignment of the deflection mirror ( 7 ) is provided, which is adjustable from the outside of the secluded space ( 13, 14 ).

The present invention is related to a device for manufacturing athree-dimensional object by a layerwise solidification of a buildingmaterial in powder form at positions in the respective layerscorresponding to the object and to a method for adjusting an opticalsystem of the same.

Such devices are e.g. known as laser sintering devices, in which thebuilding material is solidified by means of a laser beam. The beam,which is emitted from an energy source, is selectively directed toselected positions in a building plane via a scanner in order tosolidify the building material there. For a proper functioning of such adevice an exact adjustment of the beam path is necessary. An adjustmentof the beam path has to be done very carefully in order to avoidinjuries by the beam. Moreover, in known laser sintering devices arepeated deflection of the laser beam occurs between the exit of thelaser and the entrance of the scanner, such that it is folded in orderto achieve a desired characteristic of the laser beam. However, theproblem arises that an adjustment of the beam path is labor-intensiveand expensive.

In DE 10 2005 016 940 A1 a device for a layerwise manufacturing of athree-dimensional object is described, which comprises a laser sinteringdevice. In the device a building material in powder form is processed.For the application of a layer of the material in powder form a deviceis provided that comprises a powder application device, a conveyorroller and a feeding chute.

In WO 00/21736 A1 a device for manufacturing a three-dimensional objectis described, which consists of a laser sintering device. A replaceablecontainer is described, in which a work piece platform is integrated asbottom of the container. The replaceable container can be removed fromthe device, and a coupling device is provided in the device, whichcoupling device serves for mounting the container in the device and forconnecting the work piece platform to a drive.

It is an object of the present invention to provide a device of theinitially mentioned type and a method, by which an adjustment of thebeam path is made simpler and is made saver for the implementing person.Further, the optical elements shall be arranged in a narrow space havinga sufficiently long free beam path.

The object is achieved by a device according to claim 1 and a methodaccording to claim 13 or 19. Advantageous further developments aredescribed in the dependent claims.

By guiding the beam within a closed space and by providing an adjustmentmechanism for the deflection mirror from the outside a comfortable andsave adjustment of the beam path becomes possible. The provision of anaperture element in the device leads to a simplified adjustment.

By deflecting the beam from the laser to the scanner only once, anadjustment in few steps becomes possible by adjusting the alignment ofonly few components. Thus, working time in installation and serviceactivities is saved. Though a deflection occurs only once, a sufficientlength between the laser and the scanner for a proper beamcharacteristic can be achieved by a vertical arrangement of the laser ata machine frame.

Further features and advantages of the invention arise from thedescription of embodiments on the basis of the accompanying drawings, ofwhich:

FIG. 1 shows a schematic representation of a frame system according toan embodiment;

FIG. 2 shows a schematic representation of the beam guide in theembodiment according to FIG. 1;

FIGS. 3 a and 3 b show schematic detailed representations of theapertures in FIG. 2;

FIG. 4 shows a schematic perspective representation of details of aventilator system in the region of the beam guide in the embodiment;

FIG. 5 shows a schematic representation of the building space in theembodiment;

FIG. 6 shows a schematic representation of a building containerventilation system in the embodiment;

FIG. 7 shows a schematic representation of the mounting of a dosagedevice in the embodiment;

FIG. 8 shows a schematic representation of the mounting of a buildingspace heating module in the embodiment;

FIG. 9 shows a schematic representation of the mounting of anapplication device in the embodiment;

FIG. 10 shows a schematic representation of a mounting of the buildingcontainer;

FIG. 11 shows a schematic representation of a building platform seal inthe embodiment;

FIG. 12 shows a schematic representation of a building material supplysystem in the embodiment;

FIG. 13 shows a schematic representation of an application system in theembodiment;

FIG. 14 shows a schematic view of a layer to be used in a beamadjustment method; and

FIG. 15 shows a further schematic representation illustrating thebuilding material supply system.

With respect to FIGS. 1 and 5 in the following the basic construction ofa device for manufacturing a three-dimensional object by a layerwisesolidification of a building material is described, which according toan embodiment is constructed as laser sintering device. In the devicefor a manufacturing of a three-dimensional object layers of a buildingmaterial are subsequently applied on one another and the positionswithin each layer that are corresponding to the object to bemanufactured in each layer are selectively solidified before theapplication of a subsequent layer. In the described embodiment abuilding material in powder form is used, which is solidified by theaction of an energy beam on selected positions. In the describedembodiment the building material in powder form is locally heated at theselected positions by means of a laser beam such that it is connected tonearby constituents of the building material by sintering or melting.

As shown in FIG. 1 the laser sintering device comprises an opticalsystem, wherein the components of the optical system are attached to thecomponents of the machine frame. A building space 10, which isschematically represented in FIG. 5, is provided in the machine frame.

In the described embodiment the optical system comprises a laser 6, adeflection mirror 7 and a scanner 8. The laser 6 generates a beam 9 thatis incident on the deflection mirror 7 and is deflected by thedeflection mirror 7 towards the scanner 8. Alternatively, a differentenergy source such as a different radiation source that generates anenergy beam, which is directed towards the scanner 8, may be usedinstead of the laser. The scanner 8 is constructed in a known mannersuch that it can direct the incident beam 9 to arbitrary positions in abuilding plane 11 that is located in the building space 10 as shown inFIG. 5. In order to make this possible, an entrance window 12 isprovided in an upper partition wall 56 of the building space 10 betweenthe scanner 8 and the building space 10, wherein the entrance window 12enables a passing of the beam 9 into the building space 10.

With respect to FIG. 5 in the following the building space of the devicein the embodiment is described.

As can be seen in FIG. 5, in the building space 10 a container 25, whichis open to the top, is provided. A support device 26 for supporting athree-dimensional object to be formed is arranged in the container 25.The support device 26 can be moved back and forth in the container 25 ina vertical direction by means of a drive that is not shown. The buildingplane 11 is defined in the region of the upper edge of the container 25.The entrance window 12 for the beam 9 that is directed onto the buildingplane 11 by means of the scanner 8 is arranged above the building plane11. An application device 27 is provided for applying building materialthat is to be solidified onto the surface of the support device 26 oronto a layer that has previously been solidified. The application device27 can be moved over the building plane 11 in a horizontal direction bymeans of the drive that is schematically indicated by the arrows in FIG.5. On both sides of the building plane 11 dosage devices 28 and 29,respectively, are provided, which provide a predetermined amount of thebuilding material for the application device 27 in order to be applied.

On the side of the dosage device 29 a supply opening 30 is provided. Thesupply opening 30 extends over the whole width of the building plane 11in a direction that is perpendicular to the plane of FIG. 5. The supplyopening serves for supplying building material to the building space,which in the shown embodiment is a powder material that can besolidified by means of radiation.

The building space in the embodiment is subdivided into an upper region40 and a lower region 41, as is schematically shown in FIG. 5. The upperregion 40 forms the actual work space, in which a layerwise applicationof the building material and its selective solidification are carriedout. The lower region 41 accommodates the container 25.

In the shown embodiment some parts are formed by means of a method for alayerwise manufacturing of a three-dimensional element by selectivelysolidifying positions in the respective layers that correspond to theobject. In the embodiment a laser sintering method is used for themanufacturing of the objects. With respect to conventional methods formanufacturing three-dimensional objects such as milling, turning,casting, etc., such a method particularly has an advantage, when complexgeometries shall be generated and/or only relatively low quantities needto be manufactured.

Operation of the Device

When operating the device 1, the building material is supplied to thebuilding space 10 via the supply opening 30, and a pre-determined amountof the material is supplied to the application device 27 by means of thedosage devices 28, 29. The application device 27 applies a layer of thebuilding material onto the support device 26 or a previously solidifiedlayer and the beam 9 is directed to selected positions in the buildingplane 11 by means of the laser 6 and the scanner 8 in order toselectively solidify the building material in those positions thatcorrespond to the three-dimensional object to be formed. Afterwards thesupport device is lowered by the thickness of one layer, a new layer isapplied and the process is repeated until all layers of the object to beformed have been generated.

In the following several components of the device are described in moredetail.

Frame Structure

At first the frame structure of the device of the shown embodiment isdescribed based on FIG. 1. The device 1 comprises a machine frame, whichis formed by three fundamental beams 2, 3 and 4, which are connected toeach other by cross-bracings 5. The three fundamental beams 2, 3 and 4are substantially vertical and form three corners of the device in theshown embodiment. In a plane view the device 1 thus substantially hasthe outline of a triangle. The fundamental beams 2, 3 and 4 and thecross-bracings 5 are arranged such that the outline substantiallycorresponds to the one of a right angle triangle, where the hypotenuseforms the front side of the device. The cross-bracings 5 aresubstantially horizontal and connect the fundamental beams such that arigid, warp-resistant machine frame is formed, the components of whichdo not change their relative positions or only minimally change theirrelative positions, even when there is a unilateral action of forces.

Due to the design with three fundamental beams 2, 3 and 4 that arebasically extending in a vertical direction and are arranged in theshape of a triangle, the device 1 can be supported at three positions ona substrate. Due to this construction having three legs the device canbe arranged in a quick and uncomplicated way such that a jiggling ortilting with respect to the substrate is prevented. In particular, achange of the alignment with respect to the substrate may be achieved bychanging the height of the support of one of the three support points,because this leads to a rotation around the line connecting the othertwo support points. With a four-point or multi-point support for achange of the alignment the height of at least two support points wouldhave to be changed in order to achieve a stable support.

Each of the fundamental beams 2, 3 and 4 has a roller 50 and aheight-adjustable support leg 51 arranged at its bottom side facing theground. The support legs 51 are arranged on the correspondingfundamental beams 2, 3 or 4 such that they are adjustable in height.Each of the support legs 51 can be moved to a first position, in whichthe corresponding roller 50 has a larger distance to the bottom side ofthe respective fundamental beam than the bottom side of the support leg51 has. Thus, in this first position the device 1 stands on the rollers50 and the support legs 51 have a distance to the substrate. The rollers50 are pivoted on the fundamental beams 2, 3 and 4, such that the device1 can be moved over the substrate in arbitrary directions on the rollers50. Also, each of the support legs 50 can be moved to a second position,in which the bottom side of the support leg 51 sticks out more from thebottom side of the respective fundamental beam 2, 3 or 4 than therespective roller 50. In this position, the device 1 is standing on thesupport legs 51 and a movement of the device 51 relative to the supportcan be reliably prevented.

In the shown embodiment for each of the support legs 51 the side that isfacing the respective fundamental beam 2, 3 or 4 is designed as threadedrod having an external thread. Corresponding bores having an insidethread, into which the support legs 51 may be screwed, are provided inthe bottom side of the respective fundamental beams 2, 3 and 4. Thus, byscrewing a support leg 51 into the respective fundamental beam 2, 3 or 4or unscrewing it, the distance of the bottom side of the support leg 51from the fundamental beam can be continuously adjusted.

Two spirit levels 52 are mounted on the machine frame in two differentpositions. The spirit levels 52 are attached to the device 1 such thatthey are aligned in a stationary way. In the shown embodiment bothspirit levels 52 are arranged in a plane, which is in parallel to thehorizontal plane. In this plane, they have an angle of about 90° to oneanother. Both spirit levels indicate whether the device 1 is optimallyaligned with respect to the horizontal plane. For an alignment of thedevice 1 the height of each of the three support legs 51 can be changed.The change of the alignment of the device 1 can be visually controlledby the spirit levels 52. The components inside of the device arepre-adjusted with respect to each other. As they are rigidly mounted inthe frame system and because of the stiff frame construction of thedevice 1 their relative position is maintained. Thus, after an alignmentof the device 1 all components, for which an exact spatial positioningwith respect to each other is necessary for a proper function, are inthe correct relative position. The spirit levels facilitate an uprightpositioning of the device. As a result a fast and efficient alignment ofthe device 1 after a transport or a change of its position is possible.The construction having three fundamental beams 2, 3, 4 andcorresponding support legs 51 contributes to the fact that the device 1can be aligned in few steps.

Optical System

Based on FIGS. 1, 2 and 4 in the following the optical system isdescribed in more detail. The energy source, which is designed as laser6, is arranged in one of the vertical fundamental beams 2 of the machineframe or parallel to such a fundamental beam and is adjustably connectedwith it, as can be seen in FIG. 1. The beam 9 that is emanated from thelaser 6 is guided through a pipe 13. One end of the pipe 13 is connectedto the casing of the laser 6 and the other end of the pipe is connectedto a casing 14, which encloses the deflection mirror 7 and furthercomponents. Thus, the beam 9 runs from the laser 6 to the deflectionmirror 7 in a vertical direction. The casing 14 comprises a sidewall 14a that can be removed from the casing 14, as can be seen in FIG. 4. FIG.2 shows the casing 14 having the sidewall 14 a removed.

As can be seen in FIGS. 2 and 4 an end of the casing 14 that is facingaway from the pipe 13 is connected to an input side of the scanner 8 andthe casing 14 is fixedly connected to the components of the machineframe. Thus, the pipe 13 and the casing 14 are arranged such that thebeam 9 from the laser 6 runs to the scanner 8 inside of the pipe 13 andthe casing 14 in a space that is secluded from the outside. A shutter15, which is only schematically shown in the figures, is provided at thejoint between the pipe 13 and the casing 14. The shutter 15 is designedsuch that the optical path of the beam 9 from the laser 6 to thedeflection mirror 7 is interrupted, when the sidewall 14 a is removedfrom the casing 14. By this construction it is guaranteed that no injuryto an operator occurs inadvertently due to inattention, when the energysource operates and the sidewall 14 a is removed. In the embodiment theshutter 15 is implemented by a mechanical slide, which blocks a beampassage from the pipe 13 to the casing 14, when the sidewall 14 a isremoved.

As can be seen in FIGS. 1 and 2, the deflection mirror 7 deflects thebeam 9 to an entrance region 8 a of the scanner. The deflection mirror 7is suspended such that its alignment can be adjusted and it is providedwith an adjustment mechanism 16 for adjusting its alignment. Theadjustment mechanism 16 includes two actuators 17 and 18, each of whichis arranged such that a drive 17 a and 18 a, respectively, of theactuators 17 and 18 is located outside of the casing 14. Thus, thedrives 17 a and 18 a can be accessed from the outside when the casing 14is closed and the alignment of the deflection mirror 7 can be changed,when the casing 14 is closed. In the shown embodiment each of theactuators 17 and 18 is designed as mechanical set screw, which has ascale in the region of the drives 17 a and 18 a, which scale correspondsto the alignment of the deflection mirror. The drives 17 a and 18 a aredesigned as adjusting knobs. In the shown embodiment the actuators 17and 18 are manufactured by a laser sintering method. The adjusting knobsare lockable in order to prevent an inadvertent adjustment.

For an optimal functioning of the device an exact adjustment of thealignment of the beam 9 to the entrance region 8 a of the scanner isnecessary. To this end apertures 19, 20, 21, which are integrated in thecasing 14 and may be brought into the optical path, are provided. In theshown embodiment three apertures 19, 20, 21 are provided in the casing.However, also a higher or a lower number of them may be provided. In theembodiment the aperture 19 close to the deflection mirror 7 and theaperture 21 close to the entrance region 8 a of the scanner 8 both aredesigned as apertures having a reticle as shown in FIG. 3 a. Further,the aperture 20, which is arranged therebetween, is designed as pinhole,as shown in FIG. 3 b. For varying adjustment requirements there are alsoother designs of the apertures possible. Moreover, also several sets ofapertures may be provided, which may be replaced depending on therequirement for a necessary adjustment. Depending on the energy sourcethat is used for the beam 9, instead of the mechanical apertures alsoother elements may be provided, which are known to the skilled personand which are able to detect the position of the beam such as opticalsensors for the detection of the position of the beam.

Each of the apertures 19, 20, 21 is swivel-mounted on its retainer 19 a,20 a and 21 a, respectively, that is mounted at the casing 14. In afirst setting they are brought into the optical path and fixed. In asecond setting they are removed from the optical path and fixed. Thesuspension of the apertures can e.g. be implemented by means of an axis,around which the apertures 19, 20 and 21 are rotatable in a directionwhich is perpendicular to the optical path. The fixing of the apertures19, 20, 21 in their respective settings can, for example, be done bymeans of a knurled head screw, which is screwed onto this axis. However,many different ways of suspension are possible that are obvious to theskilled person due to his expert knowledge. For instance, a mechanism ispossible, in which the apertures can be engaged in both positions.

As is merely schematically shown in FIG. 1, the scanner 8 is alsoattached to another component of the machine frame. In the shownembodiment the scanner 8 is mounted to a cross bracing 5. In theembodiment the scanner 8 is suspended such that an adjustment of thealignment of the scanner is possible by rotating it around an axis thatis parallel to the optical path from the deflection mirror 7 to theentrance region 8 a of the scanner. For this adjustment an adjustmentmechanism 8 b is provided. This makes an easy and quick fine adjustmentof the alignment of the scanner 8 possible.

The beam 9 from the laser 6 to the scanner 8 is deflected only once. Itis deflected via the deflection mirror 7, wherein the alignment of thedeflection mirror 7 can be adjusted, when the casing 14 is closed. Thisleads to an optical path that can easily be adjusted by adjusting theposition of few components. Thus, in the shown embodiment only anadjustment of the position of the laser 6, of the deflection mirror 7and of the scanner 8 is necessary. The position of the laser 6 can beadjusted via an adjustment mechanism 6 b. Each one of the laser 6, thedeflection mirror 7 and the scanner 8 is directly fixed at thecomponents of the rigid frame system. Therefore, in the event of atransport or a change of location of the device 1, the laser 6, thedeflection mirror 7 and the scanner 8 do not change their relativepositions to each other or do only slightly change their relativepositions. Accordingly, a fine adjustment can be done within a shorttime and thus in an efficient way.

For an adjustment of the optical path each one of the apertures 19, 20and 21 can be brought into the beam path individually or in combinationwith the other apertures. This additionally improves the possibility ofadjusting the optical path in a quick and efficient way. Thus, it ispossible to save costs when commissioning and servicing the device 1,because there is less effort necessary for an adjustment.

Method for Adjusting the Beam

Possible methods for adjusting the beam path are described.

In one method one of the two reticle apertures 19 and 21 is brought intothe optical path and an illumination paper is inserted immediatelybehind the reticle. Then, the illumination paper is illuminated with alaser pulse and the shadow image of the reticle is evaluated. The centreof the beam cross-section should be exactly coincident with the centreof the cross. The beam path is readjusted by adjusting the alignment ofthe deflection mirror 7 via the actuators 17 and 18 and by adjusting theposition of the laser 6. This method is suitable also in a case, inwhich the beam path initially deviates very much from the desired path.When using this method it is also possible to additionally insert thepin hole 20 into the beam path.

In a method for readjusting the optical system the aperture 20, which isdesigned as pin hole, is inserted into the optical path and afterwardsthe casing 14 is closed. A power measuring device, which measures thetotal power of the beam 9, is positioned in the building plane 11. Thescanner 8 is driven in such a way that the beam 9 for the case of anexact adjustment would be optimally directed to the power measuringdevice. The beam power, which is measured by the power measuring device,is monitored and the alignment of the deflection mirror 7 is varied byoperating the actuators 17 and 18. The alignment of the deflectionmirror 7 is varied until the power measuring device measures the maximumbeam power. In such position the beam 9 is optimally directed to theentrance region 8 a of the scanner 8 by the deflection mirror 7. Thismethod can also be performed without any pin hole, so that the entranceopening at the scanner 8 takes over the function of an aperture.

This way of adjustment makes possible a simple and quick adjustment ofthe beam path in a case, in which only a small mutual change of thepositions of the components of the optical system has occurred andmerely a fine adjustment is necessary. By the method an adjustment canbe carried out within a short time and the costs of the adjustment in acommissioning and in a service can be reduced. Depending on theadjustment requirement it is also possible to perform this methodwithout an initial insertion of the pin hole 20 into the optical path.In this case there is a further saving of time and the labor costs arereduced.

In a further method a layer 110 of a material that is sensitive for anirradiation with the beam 9, e.g. a paper that changes color by atemperature effect, is positioned in a defined region in the buildingplane 11. At few selected positions at the edge of the constructionfield, which is to be irradiated by the laser 9 in a manufacturingprocess, the layer 110 is provided with marks 111, as shown in FIG. 14.Afterwards those positions, which for a correct adjustment wouldcorrespond to the marks 111, are exposed to the beam 9 via the scanner8. Then the deviations of the exposed positions from the marks 111 onthe layer 110 in two directions are determined. In its simplest way themeasurement can be performed for example by a ruler. On the basis of themeasured boundary points it is then determined, whether with respect tothe optical adjustment for example magnification errors or a tiltingoccurred. The errors that occurred can be determined for example byfeeding the measured values into a corresponding evaluation program.

Magnification errors may e.g. result from mechanical distance variationsbetween the scanner 8 and the construction field in the building plane11 or from an electronic drift of the electronic components of thescanner 8. Tilting errors may e.g. result from mechanical distance andangle variations, respectively. Magnification errors and/or tiltingerrors that have been found, depending on the error that has been found,may be compensated by the above-described fine adjustment such as areadjustment of the horizontal alignment of the scanner 8, or bycalculating correction parameters, which are used for correcting theaiming points of the laser 9 by programming in a control program fordriving the scanner 8.

In the method only individual measurement points at the edge of theconstruction field are measured. For points of the construction fieldbetween the measurement points a determination of the error is done byinterpolation. The error correction for points between the measurementpoints is also done by interpolation. Thus, only few measurement pointshave to be recorded, which may be done in a short time and with a smalleffort. Accordingly, the labor time incurred for adjustment and servicework can be considerably reduced and therefore also the operating costsincurred can be lowered.

Laser and Optics Cooling

With respect to FIGS. 1, 2 and 4 in the following a ventilation systemfor the optical system is described.

Inside of the fundamental beam 2 there is a hollow space 53, in whichthe laser 6 and the pipe 13 are located. Two ventilators 54 areprovided. The ventilators 54 generate an airflow T that leads away warmair from the laser 6 and therefore cools it. In the embodiment theventilator 54 is provided in the region of the pipe 13 in the hollowspace 53. The hollow space 53 is connected via two tubes 55 to theregion of the device 1 above the building space 10, in which buildingspace 10 the scanner 8, the deflection mirror 7 and the apertures 19,20, 21 are provided.

As can be seen in FIG. 5, the airflow T is directed by the ventilator 54to the upper partition wall 56 of the building space 10. Thus, theairflow for cooling the energy source is also deflected towards theoptical system.

The cooling system for cooling the energy source designed as laser 6thus is used in the embodiment at the same for cooling the opticalsystem, which comprises the scanner 8, the deflection mirror 7 and theapertures 19, 20 and 21. Therefore, it becomes possible to cool allcomponents of the optical system with one ventilation system.

As the airflow T is also led onto the upper partition wall 56 of thebuilding space 10, the same ventilation system can also serve for acooling of the upper side of the building space 10 and a too strongheating of control components of the device 1, which are located abovethe building space 10, can be prevented. The cooling of the upper sideof the building space 10 is done by means of the ventilation system ofthe optical system. Therefore, no separate cooling needs to be provided,because the cooling system of the laser can be also used for leadingprocess heat from the building process to the outside of the device 1.Thus, costs can be saved and the device can be built in a compact way.

In this embodiment the hollow space 53, in which the laser 6 is located,is connected to the upper side of the building space or constructionspace 10 by means of two tubes. However, it is e.g. also possible toimplement a connection via flow channels in the machine frame itself. Itis also possible to merely provide one tube or one connection channel.Though two ventilators 54 are described, depending on the necessarycooling capacity also merely one ventilator or a plurality ofventilators 54 may be provided. The arrangement of a common ventilationsystem for the optical system and for the upper side of the buildingspace 10 is not limited to a construction, in which the energy source isa laser or in which the energy source is located in the fundamental beam2. The effect of an efficient and cost-effective cooling of the opticalsystem and of the upper side of the building space is also achieved whenusing other arrangements. However, the arrangement of the energy sourcein a fundamental beam of the frame enables a space-savingimplementation.

In the following individual components of the device 1 in the buildingspace 10 are described.

Heating Device

A heating device 31 for heating the powder bed in the container 25 andin particular for pre-heating a layer that has been applied but not yetsolidified is arranged in the building space 10 above the building plane11, as is shown in FIG. 5. The heating device is designed for example asone radiant heater or a plurality of radiant heaters such as (an)infrared radiator(s), which is/are arranged above the building plane 11such that the applied layer of the building material can be uniformlyheated. In the shown embodiment the heating device 31 is designed as atwo-dimensional radiator having a heat radiating element that iscomposed of a graphite plate. As can be seen in FIG. 8, the heatradiating element has a meandering structure.

In the shown embodiment the heating device 31 being a substantiallysquare plate having a substantially square cut at its centre below theentrance window 12 extends around the area, through which the beam 9from the scanner 8 to the building plane 11 passes.

The mounting of the heating device 31 is described with respect to FIG.8. As is shown in FIG. 8, the heating device 31 in the embodimentconsists basically of a fixture 44 and of the radiant heater 45. Thefixture 44 is received in a support 46 that is arranged in the upperregion 40 of the building space 10. The radiant heater 45 is received inthe fixture 44.

As is schematically shown in FIG. 8 by the arrows A, the fixture 44 canbe removed together with the radiant heater 45 from the support 46. Thesupport 46 is designed as a rail, into which the fixture 44 is inserted.The fixture 44 can be inserted into the support 46 and removed from itwithout a tool. Several designs are possible for the connection betweenthe fixture 44 and the support 46. An attachment may be effected forexample via springs, clamps or the like. There may be providedstructures, wherein the fixture 44 is engaged in the support 46.

The fixture 44 also has a rail-like structure, into which the radiantheater 45 is inserted. The radiant heater 45 can be introduced into thefixture 44 and can be removed from the fixture 44 without a tool. Again,as it was the case for the connection between the fixture 44 and thesupport 46, different kinds of connection between the fixture 44 and theradiant heater 45 are possible. An engagement of the radiant heater 45in the fixture 44 may be provided.

Thus, the described design of the support 46, the fixture 44 and theradiant heater 45 on the one hand makes possible to remove the fixture44 from the radiant heater 45 without the use of a tool. This isparticularly advantageous for cleaning the building space 10. On theother hand the radiant heater 45 can be removed from the fixture 44without using a tool. This is particularly advantageous for the serviceand the replacement of the radiant heater 45. The removal or replacementwithout tools of components of the heating device 31 enables a quick anduncomplicated cleaning of the device 1 and a quick and uncomplicatedreplacement of the radiant heater 45. Thereby, time can be saved duringservice and cleaning work and the device 1 will be again available forthe next working process within a shorter time.

Dosage Device

As is schematically shown in FIG. 5, in the shown embodiment each of thedosage devices 28 and 29 is formed in the shape of angulated plates,which extend over the whole width of the building plane 11 in adirection, which is perpendicular to the plane of FIG. 5. The dosagedevices 28 and 29 can be rotated like a roll around an axis that isrunning in parallel to the building plane 11, and each of the dosagedevices 28 and 29 represents a conveyor roller. The dosage devices 28,29 are formed in such a way that by the movement of the applicationdevice 27 they are driven such that they rotate by a defined anglearound their axis.

The dosage device 28 is schematically shown in FIG. 7. The dosage device29 is similar to the dosage device 28 and is not described in detail.The dosage device 28 can be removed from the device 1 and can bere-inserted without a tool. As is shown in FIG. 7, the dosage device 28comprises a central portion 28 c that is formed in the shape of anangulated plate and extends along the axis of rotation Z. The centralportion 28 c serves for dosing a defined amount of a building material.Further, the dosage device 28 comprises a first end 28 a, which in thedirection perpendicular to the axis of the rotation Z has a smallercross-section than the central portion 28 c. A second end 28 b of thedosage device 28 also has a smaller cross-section than the centralportion 28 c in the direction perpendicular to the axis of rotation Z.The first end 28 a of the dosage device 28 is connected to a suspension36 around which the dosage device rotates or together with which thedosage device 28 rotates around the axis of rotation Z. For that purposethe first end 28 a and the suspension 36 are connected with each otherin a positive or form-locking way. In the shown embodiment the first end28 a has e.g. a cylindrical protrusion 28 a′, which is positivelyinserted into a recess 36′, which is also cylindrical, in the suspension36. However, the suspension 36 and the first end 28 can be designed in adifferent way. For instance the first end 28 a may have a recess and thesuspension may have a protrusion. The recess and the correspondingprotrusion may e.g. also have any other shape that leads to aform-locking connection.

The second end 28 b of the dosage device 28 is connected to a bearing37. The second end 28 b is pivot-mounted by the bearing 37. In the shownembodiment the bearing 37 has an annularly protruding edge 37 a that isconcentrical to the axis of rotation Z. The second end 28 b is designedas cylinder-shaped protrusion, which is inserted into the recess that isformed by the annularly protruding edge 37 a. However, also otherdesigns of the bearing 37 and the second end 28 b are possible. Thebearing 37 can e.g. be designed as protruding pivot and the second end28 b may have a recess that is engaged by the pivot. For enabling apivoting of the dosage device 28 several implementations are possible.

Moreover, in the shown embodiment a preload element 38 is provided onthe side of the second end 28 b between the dosage device 28 and thebearing 37, wherein the preload element 38 preloads the dosage device 28towards the suspension 36. In the embodiment the preload element 38 isformed by a helical spring that is provided coaxially to the axis ofrotation Z on or around the edge 37 a and the second end 28 b. However,alternative embodiments are also possible. For instance, the pre-loadelement can be designed in the shape of a leaf spring, the preloadelement can be provided in the bearing 37 or in the second end 28 b andthe second end 28 b itself can be moveably mounted on the dosage device28 by the preload element.

In the shown embodiment the distance between the bearing 37 and thesuspension 36 is larger than the length of the dosage device between thefirst end 28 a and the second end 28 b by a predetermined distance. Thepredetermined distance is slightly larger than the length of theprotrusion 28 a′ in the direction of the axis of rotation Z. Due to thisdesign the dosage device 28 can be moved against the preloading force ofthe pre-load element 38 into the direction of the bearing 37, so thatthe form-locking engagement between the first end 28 a and thesuspension 36 can be released. Then the dosage device 28 can be takenout and can e.g. be cleaned or be replaced by another dosage device. Theinsertion of the dosage device 28 takes place by using the reversedsequence of method steps.

Thus, the described embodiment makes it possible to remove the dosagedevice 28 without the use of a tool. The removal and the replacement ofthe dosage device 28 without a tool enable a quick and uncomplicatedcleaning of the device 1 and a quick and uncomplicated replacement ofthe dosage device 28. Thereby time can be saved during service andcleaning work and the device is again available for the next productionprocess within less time and the operating costs of the device 1 can belowered.

Alternatively, e.g. the bearing 37 and/or the suspension 36 may beconfigured as a drive shaft, which drives the dosage device such that itrotates. In such a case a form-locking connection can also be usedbetween the second end 28 b and the bearing.

The receptacles on both sides of the dosage device 28, in which thelatter is mounted, can for example be designed as recesses, into whichthe dosages device 28 is laterally inserted. A fixing can for example beachieved by the using of springs, clamps and the like. There may beprovided structures, in which the dosage device 28 engages in itsmounting. The dosage device 28 can e.g. also be fixed by means of aknurled head screw that may be tightened and released by hand.

Building Material Supply/Thermal Protection

With respect to FIG. 5 the region of the dosage devices 28 and 29 in thebuilding space 10 is described.

In the region of the dosage device 29 a building material accommodationregion 23 is formed, which is extending beneath a plane, within whichthe building plane 11 is located. The building material accommodationregion 23 is formed such that it can accommodate a limited amount ofbuilding material that is supplied by the application device 27. In theregion of the dosage device 29 and the supply opening 30 a buildingmaterial accommodation region 24 is formed. The building materialaccommodation region 24 is dimensioned such that it can accommodate thebuilding material, which is supplied via the supply opening 30, and alsothe building material that is returned by the application device 27.

The dimensions of the building material accommodation regions 23 and 24and of the dosage devices 28 and 29 are matched to each other such thatby each turn of the dosage device 28 or 29 by 180° a defined amount ofthe building material is moved in front of the application device 27.

As is shown in FIG. 5, above the dosage devices 28 and 29 radiationprotection shields 32 and 33, respectively, are mounted. The radiationprotection shields 32 and 33 prevent a heat radiation from the heatingdevice 31 from directly acting on the building material that is locatedin the region of the dosage devices 28 and 29 and in the region of thesupply opening 30 and in the building material accommodation regions 23and 24.

The lower side of the building material accommodation regions 23 and 24is provided with a double wall structure, by which hollow spaces 34 and35 are formed. The hollow spaces extend across the whole lower side ofthe building material accommodation regions 23 and 24. By this doublewall structure the building material accommodation regions arebottom-insulated with respect to the components of the device 1 locatedbeneath them. According to one embodiment a fluid can be circulatedthrough the hollow spaces 34 and 35 in order to adjust the temperatureof the building material in the building material accommodation regions23 and 24. Also, a control device may be provided that controls the flowrate of the fluid through the hollow spaces 34 and 35 and/or thetemperature of the fluid. By providing such a control device thetemperature of the building material can be controlled.

By providing the radiation protection shields 32 and 33 and the hollowspaces 34 and 35 the temperature of the building material in the area ofthe dosage devices 28 and 29 and the powder accommodation regions 23 and24 can be kept at a lower value than the temperature of the buildingspace above the building plane 11 and the temperature of the regionbelow the container 25.

Thus, by providing the hollow spaces 34 and 35 and the radiationprotection shields 32 and 33 a too high rise of the temperature of thebuilding material in the building material accommodation regions 23, 24,which is not desired, is prevented. Thereby the danger of thermallyaffecting the properties of the building material before the buildingprocess, which is undesirable, may be reduced.

Application System

In the following the application system in the embodiment is describedwith respect to FIGS. 9 and 13.

As can be seen in FIG. 13, the application system comprises theapplication device 27 and a drive mechanism 59. The application device27 comprises the application element 61 and a holder 60. The applicationelement 61 is held in the holder 60. The holder 60 is connected to thedrive mechanism 59.

As can be seen in FIG. 9 the holder 60 comprises a main arm 62 and twoholder arms, a first holder arm 63 and a second holder arm 64, which arevertically extending from the main arm 62 in a downward direction. Thefirst holder arm 63 is rigid and is fixedly connected to the main arm62. The second holder arm 64 has one end 64 a that is fixedly connectedto the main arm 62. The second holder arm 64 has flexibility, such thatits free end 64 b can be moved to a limited extent against a restoringforce of the material of the second holder arm 64, as is indicated inFIG. 9 by the arrow C. By this movement the distance between the freeends 63 b, 64 b of the holder arms 63, 64 can be increased. In each ofthe holder arms 63 and 64 a recess 63 c and 64 c, respectively, isprovided.

The application element 61 comprises a main body 61 a, which extendssubstantially in parallel to the main arm 62 of the holder 60, and twoprotrusions 61 b, which protrude laterally from the main body 61 a. Thetwo protrusions 61 b are dimensioned such that they can be inserted in aform-locking way into the recesses 63 c and 64 c of the holder arms 63and 64. The form-locking engagement brings about a torque proofconnection between the application element 61 and the holder 60. In theshown embodiments the application element 61 is designed as applicationblade, which has a lower edge 61 c that effects the application of thebuilding material and a smoothing of the same.

As is schematically shown in FIG. 9 by the arrows C and D, the free end64 b can be moved away from the free end 63 b in the direction of thearrow C, so that the form-locking engagement between the applicationelement 61 and the second holder arm 64 is released. Then theapplication element 61 can be removed from the holder 60, as isindicated by the arrow D.

A mounting of the application element 61 to the holder 60 is done in thereverse order.

By the described design the application element 61 can be released fromthe holder 60 and mounted on the holder 60 in a tool-less way, i.e.without using a tool. Thereby a quick and efficient exchange of theapplication element 61 is made possible. Time can be saved duringservice and cleaning work and the device 1 is in less time againavailable for the next production process. In particular, differentapplication elements 61 can be used for subsequent building processesdepending on the respective requirements and these application elements61 can be changed between the building processes with a small effort.

Other configurations for connecting the application element 61 with theholder 60 are possible. For instance, recesses may be provided at theapplication element 61 and protrusions may be provided at the holder 60for a form-locking connection. For instance, also an insertion into agroove and optionally an engagement between the application element 61and the holder 60 may be provided.

The drive mechanism 59 of the application system 27 is described withrespect to FIG. 13. As can be seen in FIG. 13, the holder 60 of theapplication device 27 is connected to a drive shaft 65 in a torque proofway. The drive shaft 65 is pivot-mounted at its ends in bearings 66 and67. The drive shaft is rotatable around an axis E that is perpendicularto the building plane 11, which is shown in FIG. 5. The rotation isindicated by the arrows F in FIG. 13. Further, a lever 68 is mounted onthe drive shaft 65 in a torque proof way. The lever 68 is connected toan actuation piston-cylinder system 69. Further, the lever 68 isconnected to a break piston-cylinder system 70. In the embodiment theactuation piston-cylinder system 69 is designed as pneumatic system,which drives the drive shaft 65 such that the drive shaft 65 rotatesaround the axis E, when the piston is charged with pressure via thelever 68. The rotation of the drive shaft 65 results in a rotation ofthe holder 60, so that the application element 61 is set in motion inparallel to the building plane 11. The drive shaft 65 is arrangedlaterally to the construction field or building field, in which thesolidification of the building material is carried out, in the backregion of the building space. Via the drive mechanism 59 the applicationdevice 27 can be moved on a path across a limited angular range, whereinthe path corresponds to a sector of a circle. Thus, the applicationdevice 27 is moved back and forth on a circular path between a firstposition on one side of the construction field and a second position onthe opposite side of the construction field. Due to this configurationthe drive mechanism 59 for moving the application device 27 is arrangedsubstantially on one side of the construction field and an unimpededaccess to the construction field from the opposite side is ensured. Byproviding the pneumatic system as drive the motion of the applicationdevice can be implemented with high precision and at the same time at alow cost.

The break piston-cylinder system 70 is designed as an oil dashpot. Thebreak piston-cylinder system 70 effects a damping of pressurevariations, when the actuation piston-cylinder system is charged, or ofvariations of the resistive force that is countering the drive, whichchanges would effect an abrupt change of the velocity of the applicationdevice 27. Thus, a uniform movement of the application device 27 with apredetermined velocity profile is enabled. The optimized motion of theapplication device 27 leads to an improved uniform application of alayer and thus to an improvement of the part quality.

In the embodiment an application device 27 is described, which moves ona circular path around the axis E in parallel to the building plane 11.The circular path is dimensioned such that the application device 27performs a movement across the whole building plane 11. The applicationdevice can also be configured such that a linear movement across thebuilding plane 11 is implemented. In this case the combination of theactuation piston-cylinder system 69 with the break piston-cylindersystem 70 also leads to a more uniform movement of the applicationdevice and thus to an improved layer application.

Replacement Container/Suspension

The configuration of the container 25 in the embodiment is describedwith respect to FIGS. 5 and 10. In FIG. 5 the container 25 having thesupport device 26 arranged therein is only shown schematically.

In the embodiment the container 25 is designed as a replacementcontainer or swap container, which can be taken out of the device 1together with the support device 26, which forms a building platform andis located therein. A coupling mechanism that is not shown is providedin the device 1. By the coupling mechanism the connection of the supportdevice 26 and the container 25 to the drive for vertically moving thesupport device 26 can be established and released. This couplingmechanism is driven by a control of the device 1. The coupling mechanismcan be configured such that it is similar to the one that was describedin the prior art mentioned in the introduction.

As is schematically shown in FIG. 10, a mounting 74 is provided at adoor 73. The door 73 is swivel-mounted at the machine frame of thedevice 1 and in a closed state secludes the building space 10 of thedevice 1 from the outside of the device 1. In the embodiment the door 73is mounted at one side such that it can be pivoted around an axis G asis indicated by the arrow H. In the shown embodiment the axis G runsvertically, so that the door 73 of the device 1 swings open to the side.

The container 25 comprises on the one side an attachment 75. Theattachment 75 can be brought into an engagement with the mounting 74 inthe door 73 such that the container 25 is supported at the door 73 andtogether with the door 73 can swing open from the machine frame. In theshown embodiment the mounting 74 is formed on the inner side of the door73 as a protrusion that has a recess at its top side. The attachment 75at the container 25 is designed as a protruding hook, which engages intothe recess.

In order to insert the container 25 into the device 1 the attachment 75of the container 25 is engaged with the mounting 74 with the door 73being open. This procedure can be comfortably carried out, because themounting 74 is easily accessible from the outside of the device 1, whenthe door 73 is open. The container 25 is decoupled from the mounting 74via the coupling mechanism by means of the control of the device 1. Thesupport device 26 is connected to the respective drive.

In this state the container 25 is not connected with the door 73 and thedoor 73 can be opened if necessary without taking the container 25 outof the device 1. On the other hand by the control of the device 1 thecontainer 25 can be re-engaged with the mounting 74 and the supportdevice 26 can be decoupled from the respective drive. In this state thecontainer 25 can be moved out of the building space 10 and out of thedevice 1 by opening the door 73. The container 25 swings out togetherwith the door 73. In this position the container 25 can be comfortablytaken out of the device, wherein it is not necessary to reach into theinside of the machine.

Though in the embodiment the door 73 is swivelled around a verticalaxis, it is e.g. also possible to provide a door that opens horizontallyin a different way. Moreover, the connection between the door 73 and thecontainer 25 is not limited to the described embodiment having recessand an engaging hook. Also other mechanisms can be provided that enablean engagement of the door 73 with the container 25.

Building Platform Sealing

The guide of the support device 26 in the container 25 is described withrespect to FIG. 11. As was already described with respect to FIG. 5, thesupport device 26 can be moved in a vertical direction K relative to thecontainer 25 via a drive. The upper side of the support device 26 formsthe building platform 78, on which the three-dimensional object to beformed is generated layer-wise. Between the building platform 78 and theinside wall 79 of the container 25 there is a gap 80 that is dimensionedsuch that the support device 26 can be moved inside of the container 25in a vertical direction. There is the danger that the building materialgets from the region of the building platform 78 via the gap 80 into theregion in the container 25 underneath the building platform 78. Thepassing of building material is however not desired, because acontamination of the drive may occur and as a result service work willbe necessary.

In order to avoid a passing through of building material, the gap 80 isclosed by a seal 81 that is described in the following. The seal 81 isformed by a layer of a flexible material, which is annularly arrangedalong the edge of the building platform 78 underneath the buildingplatform 78. The seal 81 is for example made of a flat strip of asilicone material. However, also other materials, which have asufficient temperature resistance and flexibility, are possible. In aflat state the seal 81 has an outer dimension in the plane perpendicularto the movement or shifting direction K, which is slightly larger thanthe inner dimension of the container 25. Thus, when it is inserted inthe container 25, the seal 81 is slightly bent in the zone of the gap 80and butts against the inside wall 79 of the container 25 with a smalltension due to the flexibility of its material.

Underneath the building platform 78 a guide plate 82 is arranged underthe seal 81. In a plane, which is perpendicular to the direction ofmovement K, the guide plate 82 has a slightly larger outer dimensionthan the building platform 78. The circumferential outer edge 82 a ofthe guide plate 82 is angled towards the gap 80. The outer edge 82 abutts against the seal 81 in the zone of the gap 80. The outer edge 82 abends the seal 81 in the region of its outer circumference, so that theedge of the seal 81 in the gap is angled towards an upper boundary ofthe space. Even when the building platform 78 is moved in a directionopposite to the bending direction of the angulated edge region of theseal 81, the guide plate 82 prevents the flexible seal 81 from foldingdown in its edge region opposite to its pre-shaped direction. Thus, itis ensured that the support device 26 together with the buildingplatform 78 can be reliably shifted relative to the container 25 in theshifting direction K. Moreover, a passing of particles of the buildingmaterial into the region underneath the building platform 78, whichwould be able to occur when the seal folds down, is prevented.

Further, the guide plate 82 having the angled edge region 82 a has theeffect that a plane plate made of e.g. silicone can be used as seal 81.The seal 81 can e.g. also be made from a different plastic. Based onthis implementation the seal need not have at its outer edge in thecircumferential direction a special structure or shaping that is adaptedto the exact dimension of the inner diameter of the container.

Tempering of the Container

The lower region 41 of the building space 10 is described with respectto FIGS. 5 and 6. As can be seen in FIG. 5, a chamber 85 is formed inthe lower region 41, wherein the chamber 85 surrounds the lower side ofthe container 25. When operating the device 1, the chamber 85 is filledwith a fluid medium. In the embodiment the fluid medium is a gas. Inparticular, in one embodiment this gas is an inert gas, which is alsoused in the upper region 40 in order to prevent a deterioration of thebuilding material by e.g. oxidation.

The chamber 85 is laterally limited by side walls 86 and at the top isseparated from the upper region 40 of the building space 10 by aseparating plate 87 at the height of the building plane 11. The chamber85 is bounded below by a bottom 88. The bottom 88 comprises a passage 89for a connection of the support device with its drive in the regionbelow the container 25. In the bottom 88 in a region under the cornersof the container 25 outlets 90 are provided. In the shown embodimentunder each corner of the container 25 two outlets 90 are provided.However, also a different number of outlets may be provided, e.g. onlyone outlet may be provided for each corner.

Moreover, in the side walls 86 openings 91 are provided in the upperpart, as can be seen in FIG. 5. The openings 91 are connected to theoutlets 90 via a ventilation system. In the embodiment the ventilationsystem is arranged outside of the chamber 85 and is formed by a secondchamber 84 outside of the side walls 86 and under the bottom 88. Aventilator 92 is located in the ventilation system. Moreover, a heatingdevice 93 and a temperature sensor are provided in the ventilationsystem. By the ventilator 92 the fluid medium in the lower region 41 issucked through the openings 91 into the second chamber 84 and a directedflow of this medium is re-introduced through the outlets 90 into thechamber 85. Due to the positioning of the outlets 90 underneath thecorners of the container 25 and due to the openings 91 in the side walls86 a directed flow is generated in the region of the corners of thecontainer 25, which directed flow effects a temperature adjustment orbalancing of the container 25. This flow is indicated by the arrows S inFIGS. 5 and 6. By this flow the temperature profile of the container 25can be defined and a uniform tempering of the container 25 is possible.By providing the heating device 93 and the temperature sensor an exactadjustment of the temperature of this flow is possible. Thus, thetemperature of the container 25 and of the building material locatedtherein can be adjusted in a defined way during the operation of thedevice 1. The flow causes a heat exchange between the fluid medium andthe container 25, in particular in the corners of the latter. Based onthe corners the temperature profile of the container 25 can be keptparticularly homogenous in an advantageous manner.

By the selective tempering of the corners of the container by means ofthe directed flow a controlled cooling of the solidified buildingmaterial and the surrounding non-solidified building material in thecontainer 25 can be carried out during the operation. Thus, when thebuilding material cools down, extreme temperature gradients, which wouldlead to a deterioration of the manufactured three-dimensional objects bywarping during the cooling down, can be prevented.

In the embodiment the same process gas that is also used in the upperregion 40 of the building space 10, which is the actual building region,is used as fluid medium. Thus, a particular sealing between the upperregion 40 and the lower region 41 of the building space 10 is notnecessary. Thus, a cost-effective construction of the device 1 is madepossible. Further, also a thermal aging of the building material in thecontainer 25 is prevented in a higher degree. This is also particularlyadvantageous with respect to a recycling of the non-solidified buildingmaterial in a further building process.

Building Material Supply

The supply of the building material to the device 1 is described withrespect to FIGS. 1, 12 and 15. As can be seen in FIG. 1, in the backwardregion of the device 1 an opening 95 for feeding the building materialis formed. The opening 95 is connected to the supply opening 30, whichleads to the building space 10 and is shown in FIG. 5. In the device 1in the region of the opening 95 a duct 96 is formed. Via the duct 96 thebuilding material is supplied to the supply opening 30. In theembodiment the supply is effected based on the intrinsic weight of thebuilding material by drop delivery. The upper region of the duct 96 isschematically shown in FIG. 12.

The duct 96 has a cover wall 97 at its top side, wherein in the coverwall two openings 97 a and 97 b are provided in order to be connected tofiller pipes 98 a and 98 b for a building material supply. The fillerpipes 98 a and 98 b have at its upper side connectors 99 a, 99 b forbuilding material supply containers 100 a and 100 b, respectively. Theconnectors 99 a and 99 b can be separately connected to the buildingmaterial supply containers 100 a and 100 b. In each of the filler pipes98 a, 98 b a gate 101 a and 101 b, respectively, is provided. Each ofthe gates 101 a, 101 b can be moved into a first position, in which thecross-section of the corresponding filler pipe 98 a and 98 b,respectively, is closed, as it is shown on the left side in FIG. 12. Thegates 101 a, 101 b can also be moved to a second position, in which thecross-section of filler pipe 98 a and 98 b, respectively, is not closedor covered and building material can pass from the building materialsupply container 100 a und 100 b, respectively, to the duct 96.

In the duct 96 below the openings 97 a and 97 b filling level sensors102 a and 102 b, respectively, are mounted. The filling level sensor 102a detects, whether building material is in the duct 96 below the fillerpipe 98 a. The filling level detector 102 b detects, whether there isbuilding material in the duct below the filler pipe 98 b.

Each of the filler pipes 98 a and 98 b is provided with a mechanism, bywhich it can be moved above the duct 96 and can be moved away from theduct 96, respectively, together with a building material supplycontainer 100 a and 100 b, respectively, as is schematically shown inFIG. 15. Both filler pipes can be moved independently. In the embodimentthis motion is a swivelling around an axis that is substantiallyhorizontal.

In operation the duct 96 is initially filled with building material. Abuilding material supply container 100 b is also filled with buildingmaterial and the corresponding gate 101 is in the open position. Acolumn of the building material extends within the duct 96 to aposition, which is higher than the respective filling level sensor 102b. The second building material supply container 100 a is also filledwith building material. However, the respective gate is still in theclosed position, as is shown in FIG. 12.

When operating the device 1, building material is consumed and thefilling level in the duct 96 falls, because the building material issupplied to the building space 10 via the supply opening 30 due to itsweight. As long as there is building material in the building materialsupply container 100 b, this building material slides along into theduct 96. When the building material supply container 100 b is empty andthe device 1 is further operated, the filling level in the duct 96 fallson the side of the filling level sensor 102 b. Then the filling levelsensor 102 b detects that the building material supply container 100 bis empty. Afterwards the gate 101 in the filler pipe 98 b is closed. Thegate 101 in the other filler pipe 98 a is opened, so that buildingmaterial is supplied to the duct 96 from the other building materialsupply container 100 a.

In this position the building material supply container 100 b can beremoved from the device 1 and can be filled or can be replaced byanother filled building material supply container. The connector 99 aand 99 b, respectively, can e.g. be designed as an inside thread in thefiller pipe 98 a and 98 b, respectively, into which a correspondingoutside thread at the building material supply container 100 a, 100 b isscrewed. This enables the use of commercially available containers asbuilding material supply containers. The filled or replaced buildingmaterial supply container can again be connected with the filler pipe 98b and can be moved over the duct 96, so that it is available when theother building material supply container 100 a is empty.

When the building material supply container 100 a is empty, the fillinglevel in the duct 96 falls and the filling level sensor 102 a detectsthis falling and outputs a signal to the control of the device 1, whichindicates that the building material supply container is empty.Afterwards the gate 101 in the filler pipe 98 a can be closed and thegate 101 in the filler pipe 98 b can be opened so that again buildingmaterial from the building material supply container 100 b can besupplied. The closing and opening of the gates 101 can be effected bythe control of the device 1. Then the building material supply container100 a can be exchanged.

Two building material supply containers 100 a and 100 b are provided,which can be independently connected to the device 1 via independentconnectors 99 a and 99 b. The operation of the device 1 need not beinterrupted, when a building material supply container 100 a and 100 b,respectively, is replaced or exchanged. The exchange of the buildingmaterial supply container can be carried with the building process beingcontinuously performed, when a three-dimensional object is manufacturedin the building space 10. An efficient operation of the device 1 isachieved and idle periods, in which there can be no building processes,can be reduced. The device 1 can be operated in a simpler way. Duringthe operation a building material supply container can always be held ina filled state.

Further, a lid for closing the building material supply containers 100a, 100 b can be provided. Then the building material supply containersmay be closed before a supply to the device 1 and after an extraction.

By designing the filler pipes 98 a, 98 b such that they have connectors99 a, 99 b for the building material supply containers 100 a, 100 b, itis possible to use in the device building material supply containers,which are also suited for storing and for mixing the building material.Depending on the design of the connector commercially availablecontainers can be used.

Moreover, also a plurality of building material supply containers may beprovided for e.g. different building materials or for a storage ofbuilding material. In particular, a plurality of building materialsupply containers can be used such that the device 1 is operated withtwo building material supply containers and at the same time a mixing ofbuilding material is carried out in further building material supplycontainers. Further, the device 1 can also be provided with oneconnector or with more than two connectors for the building materialsupply containers.

In an embodiment the control of the device 1 is configured such that thefilling level information is automatically sent electronically to theoperators by the filling level sensors 102 a, 102 b. The information cane.g. be sent via SMS or via email. To this effect the device 1 has anappropriate network connection.

It was described that the supply of the building material is effected byusing the intrinsic weight of the building material. However, the supplycan also be effected in a different way. For instance, a mechanicaldevice may be provided for the building material supply containers,which mechanical device assists in supplying the building material tothe duct. For instance, a vibration device can be used, which induces avibration of the building material supply containers 100 a, 100 b and ofthe building material therein, respectively, in order to assist thesupply of building material to the duct 96. The vibration device cane.g. be formed by one or more mechanical vibration exciters, which arearranged at the filler pipes 98 a, 98 b (filler portions).

Modifications

Modifications of the described device are possible. Instead of a laser adifferent energy source such as another light source or e.g. also anelectron source or another particle source may be used. Depending on theenergy source also other optical systems may be used. In the case of anelectron source as energy source e.g. an electromagnetic lens anddeflection system may be used. Some of the described features such asthe design of the frame system can also be implemented in e.g. devicesfor a 3D printing using a method similar to inkjet printing or in maskexposition methods.

Also when using a laser as energy source, the device can e.g. beconfigured such that it is used in a laser sintering method or such thatit is used in a laser melting method, in which the building material islocally melted.

A plurality of materials can be used as building material. For instance,a plastic powder such as a polyimide powder can be used or it is alsopossible to use metal or ceramics powders. It is also possible to usemixtures. For instance plastic-coated metals can be used.

1. A device for manufacturing a three-dimensional object by a layer-wisesolidification of a building material at the positions in the respectivelayers that correspond to the object, comprising: an energy source thatemits a beam for solidifying the building material, a scanner thatselectively directs the beam to different positions in a building planeand a deflection mirror that deflects the beam coming from the energysource to the scanner; wherein the beam from the energy source to thescanner runs in a space that is secluded from the outside and wherein anadjustment mechanism for an alignment of the deflection mirror isprovided, which can be adjusted from the outside of the secluded space.2. The device according to claim 1, wherein the adjustment mechanismcomprises an actuator that has been manufactured by a laser sinteringmethod.
 3. The device according to claim 1, wherein an adjustmentmechanism for adjusting the alignment of the scanner is provided.
 4. Thedevice according to claim 1, wherein an adjustment mechanism foradjusting the alignment of the energy source is provided.
 5. The deviceaccording to claim 1, wherein the energy source is a laser and thelaser, the deflection mirror and the scanner are arranged such that thebeam from an exit of the laser runs to the deflection mirror without afurther deflection and runs from the deflection mirror to an entrance ofthe scanner without a further deflection.
 6. The device according toclaim 1, wherein the energy source is substantially vertically arrangedin or at a fundamental beam of a machine frame of the device.
 7. Thedevice according to claim 1, wherein the beam from the energy source tothe deflection mirror runs through a pipe and a shutter is provided atthe end of the pipe that is facing the deflection mirror.
 8. The deviceaccording to claim 7, wherein the beam from the deflection mirror to thescanner runs through a casing and the shutter interrupts the opticalpath, when a removable sidewall of the casing is removed.
 9. The deviceaccording to claim 1, wherein at least one integrated aperture elementis provided in the device, which can be inserted into the beam in orderto adjust the beam path.
 10. The device according to claim 9, whereinthe aperture element is positioned between the deflection mirror and thescanner.
 11. The device according to claim 9, wherein the apertureelement is formed by a mechanical aperture that can be moved into theoptical path.
 12. The device according to claim 9, wherein the beambetween the deflection mirror and the scanner runs through a casing andthe aperture element is arranged in the casing.
 13. A method foradjusting a beam path in a device for manufacturing a three-dimensionalobject by a layer-wise solidification of a building material at thepositions in the respective layers that correspond to the objectcomprising the steps of: generating a beam path between an energy sourcethat is generating the beam and a scanner that is selectively directingthe beam to positions in a building plane via a deflection mirror thatis positioned between the energy source and the scanner in a spacesecluded from the outside; and adjusting the alignment of the deflectionmirror from the outside of the secluded space.
 14. The method accordingto claim 13, wherein in addition to the adjustment of the alignment ofthe deflection mirror also an adjustment of the alignment of the scannerand/or of the energy source is done.
 15. The method according to claim13, wherein an aperture element that is integrated in the device isinserted into the beam before the generation of the beam path.
 16. Themethod according to claim 15, wherein the aperture element is insertedinto the beam between the deflection mirror and the scanner.
 17. Themethod according to claim 13, wherein an element of the beam guidingoptics, which limits the beam diameter, is used as aperture element. 18.The method according to claim 13, wherein a power meter is placed in thebuilding plane and the alignment of the deflection mirror and/or thescanner and/or the energy source is changed until the power meterindicates a maximum power of the beam.
 19. A method for adjusting a beampath in a device for manufacturing a three-dimensional object by alayer-wise solidification of a building material at positions in therespective layers that correspond to the object comprising the steps of:driving the scanner such that the beam is directed to a plurality ofselected aiming points in the periphery of a building field in thebuilding plane and detecting the points of incidence of the beam;measuring the relative positions of the points of incidence of the beamwith respect to the required positions and calculating a necessaryre-adjustment of the deflection mirror and/or the scanner; and adjustingthe alignment of the deflection mirror and/or the scanner according tothe calculated values.
 20. The method according to claim 13, furthercomprising the steps of: driving the scanner such that the beam isdirected to a plurality of selected aiming points in the periphery of abuilding field in the building plane and detecting the points ofincidence of the beam; measuring the relative positions of the points ofincidence of the beam with respect to required positions and calculatinga necessary re-adjustment of the deflection mirror and/or of thescanner; and adjusting the alignment of the deflection mirror and/or ofthe scanner according to the calculated values.
 21. The method accordingto claim 19, wherein the deviations from the points of incidence of thebeam in the building plane between the selected aiming points in theperiphery of the building field from the respective required positionsare determined by interpolation.
 22. The method according to claim 19,wherein an alignment of the scanner is performed mechanically byadjusting its position with respect to the building plane.
 23. Themethod according to claim 19, wherein an alignment of the scanner isperformed such that, when driving the scanner, the aiming points arecorrected based on the detected points of incidence.